ShaheenGandhi.pde

   1 import toxi.geom.Vec3D;
   2 import toxi.geom.Matrix4x4;
   3
   4 class HelixPattern extends SCPattern {
   5
   6   // Stores a line in point + vector form
   7   private class Line {
   8     private final PVector origin;
   9     private final PVector vector;
  10
  11     Line(PVector pt, PVector v) {
  12       origin = pt;
  13       vector = v.get();
  14       vector.normalize();
  15     }
  16
  17     PVector getPoint() {
  18       return origin;
  19     }
  20
  21     PVector getVector() {
  22       return vector;
  23     }
  24
  25     PVector getPointAt(final float t) {
  26       return PVector.add(origin, PVector.mult(vector, t));
  27     }
  28
  29     boolean isColinear(final PVector pt) {
  30       PVector projected = projectPoint(pt);
  31       return projected.x==pt.x && projected.y==pt.y && projected.z==pt.z;
  32     }
  33
  34     float getTValue(final PVector pt) {
  35       PVector subtraction = PVector.sub(pt, origin);
  36       return subtraction.dot(vector);
  37     }
  38
  39     PVector projectPoint(final PVector pt) {
  40       return getPointAt(getTValue(pt));
  41     }
  42
  43     PVector rotatePoint(final PVector pt, final float rads) {
  44       Vec3D axisVec3D = new Vec3D(vector.x, vector.y, vector.z);
  45       Vec3D originVec3D = new Vec3D(origin.x, origin.y, origin.z);
  46       Matrix4x4 mat = new Matrix4x4().identity()
  47         .rotateAroundAxis(axisVec3D, rads);
  48       Vec3D ptVec3D = new Vec3D(pt.x, pt.y, pt.z).sub(originVec3D);
  49       Vec3D rotatedPt = mat.applyTo(ptVec3D).add(originVec3D);
  50       return new PVector(rotatedPt.x, rotatedPt.y, rotatedPt.z);
  51     }
  52   }
  53
  54   private class Helix {
  55     private final Line axis;
  56     private final float period; // period of coil
  57     private final float rotationPeriod; // animation period
  58     private final float radius; // radius of coil
  59     private final float girth; // girth of coil
  60     private final PVector referencePoint;
  61     private float phase;
  62     private PVector phaseNormal;
  63
  64     Helix(Line axis, float period, float radius, float girth, float phase, float rotationPeriod) {
  65       this.axis = axis;
  66       this.period = period;
  67       this.radius = radius;
  68       this.girth = girth;
  69       this.phase = phase;
  70       this.rotationPeriod = rotationPeriod;
  71
  72       // Generate a normal that will rotate to
  73       // produce the helical shape.
  74       PVector pt = new PVector(0, 1, 0);
  75       if (this.axis.isColinear(pt)) {
  76         pt = new PVector(0, 0, 1);
  77         if (this.axis.isColinear(pt)) {
  78           pt = new PVector(0, 1, 1);
  79         }
  80       }
  81
  82       this.referencePoint = pt;
  83
  84       // The normal is calculated by the cross product of the axis
  85       // and a random point that is not colinear with it.
  86       phaseNormal = axis.getVector().cross(referencePoint);
  87       phaseNormal.normalize();
  88       phaseNormal.mult(radius);
  89     }
  90
  91     private void setPhase(float phase) {
  92       this.phase = phase;
  93       setPhaseNormalFromPhase();
  94     }
  95
  96     Line getAxis() {
  97       return axis;
  98     }
  99
 100     void step(int deltaMs) {
 101       // Rotate
 102       if (rotationPeriod != 0) {
 103         setPhase(phase + (deltaMs / rotationPeriod) * TWO_PI);
 104       }
 105     }
 106
 107     PVector pointOnToroidalAxis(float t) {
 108       PVector p = axis.getPointAt(t);
 109       PVector middle = PVector.add(p, phaseNormal);
 110       return axis.rotatePoint(middle, (t / period) * TWO_PI);
 111     }
 112
 113     color colorOfPoint(final PVector p) {
 114       // Find the appropriate point for the current rotation
 115       // of the helix.
 116       float t = axis.getTValue(projectedPoint);
 117       PVector toroidPoint = pointOnToroidalAxis(t);
 118
 119       // The rotated point represents the middle of the girth of
 120       // the helix.  Figure out if the current point is inside that
 121       // region.
 122       float d = PVector.dist(p, toroidPoint);
 123       boolean inToroid = d < girth;
 124
 125       // Soften edges by fading brightness
 126       float b = constrain(100*(1 - ((d-.5*girth)/(girth*.5))), 0, 100);
 127       return color((lx.getBaseHuef() + (360*(phase / TWO_PI)))%360, (inToroid ? 80 : 0), b);
 128     }
 129   }
 130
 131   private final Helix h1;
 132   private final Helix h2;
 133
 134   private final BasicParameter helix1On = new BasicParameter("H1ON", 1);
 135   private final BasicParameter helix2On = new BasicParameter("H2ON", 1);
 136
 137   public HelixPattern(GLucose glucose) {
 138     super(glucose);
 139
 140     addParameter(helix1On);
 141     addParameter(helix2On);
 142
 143     h1 = new Helix(
 144       new Line(new PVector(100, 50, 70), new PVector(1,0,0)),
 145       700, // period
 146       50, // radius
 147       30, // girth
 148       0,  // phase
 149       10000); // rotation period (ms)
 150     h2 = new Helix(
 151       new Line(new PVector(100, 50, 70), new PVector(1,0,0)),
 152       700,
 153       50,
 154       30,
 155       PI,
 156       10000);
 157
 158     // TODO(shaheen) calculate line segments between
 159     // toroidal points selected by stepping the
 160     // parameterized t value.  select base pairs and
 161     // associated colors.  lerp between colors for each
 162     // base pair to produce a DNA effect.
 163
 164   }
 165
 166   void run(int deltaMs) {
 167     boolean h1on = helix1On.getValue() > 0.5;
 168     boolean h2on = helix2On.getValue() > 0.5;
 169
 170     h1.step(deltaMs);
 171     h2.step(deltaMs);
 172
 173     for (Point p : model.points) {
 174       color h1c = color(0,0,0);
 175       color h2c = color(0,0,0);
 176
 177       if (h1on) {
 178         h1c = h1.colorOfPoint(new PVector(p.x,p.y,p.z));
 179       }
 180
 181       if (h2on) {
 182         h2c = h2.colorOfPoint(new PVector(p.x,p.y,p.z));
 183       }
 184
 185       // The helices are positioned to not overlap.  If that changes,
 186       // a better blending formula is probably needed.
 187       colors[p.index] = blendColor(h1c, h2c, ADD);
 188     }
 189   }
 190 }
 191